The present invention relates in general to machines for cutting panels from continuous lengths of material, and, more particularly, to machines of the flying type.
As used herein, the term "flying" refers to a machine that moves in the material flow direction during the operation. Thus, a flyer shear is a shear that moves in the material flow direction during the shearing operation. Such flying shears are quite desirable as the downward stroke thereof does not interrupt the continuous panel forming operation, thereby increasing manufacturing efficiency.
Flying shears are well known in the art, and can be categorized in one of two general classes. One class of flying shears includes the slug forming machines. Such machines generally utilize a top blade which moves vertically and a bottom blade arrangement which includes two side blades with the top blade moving between the bottom side blades to shear a panel off. These machines thus produce a slug, or piece of material which is wasted. In production lines which produce great numbers of panels, the slug forming machines can become quite uneconomical due to the wasted material.
Another class of flying shears is the type which does not remove a slug during the cutting operation. The slugless cutoff machines have a top blade which moves at an angle with respect to the vertical to cut off a panel in a scissors-type action. Thus, the top blade moves downward and sideways to execute the cutoff operation. The slugless machines are desirable in production lines which produce great numbers of panels due to the cost savings thereof as compared to the slug forming type machines as there is no wasted slug material in the slugless machines. Examples of slugless cutoff dies are shown in literature published by the Hill Engineering Company.
In many panels, the cut end will be the top or the bottom of the panel. Therefore, it is desirable to place an attachment hole of some type at this location. Thus, it is desirable to incorporate a flying punch with the flying shear mechanism. Such flying punch can be located either upstream or downstream of the shear, with respect to the material flow direction. It may even be desirable to locate punches both upstream and downstream of the shear. As used herein, a flying punch is a punch which executes the punching movement while moving in the material flow direction.
In order to define a precise hole, the punch must move vertically with respect to the panel. This requirement appears to preclude use of such punch-shear combinations on the slugless machines due to the sideways component of the blade movement. Indeed, nowhere in the prior art is there any such combination of a flying punch which punches as a cut is being made in a slugless flying shear.
Heretofore, the punching and cutting functions have been performed sequentially and separately rather than concurrently. Thus, one known method includes making a cut to define a panel, then following the cutting step, performing a flying punch operation on the free panel. In such a procedure, the sheared panel is loose and therefore has a tendency to move. In such a case, a punched hole has a tendency to be misshapen and imprecise. Furthermore, there is considerable wear produced on the punches.
A second known method punches first, and then shears the panel. Again, even though the material is not free, as in the first method, there is a danger of elongated holes and wearing and breaking of punches.
If the flying punch is used on the slug forming machine, the vertical movement of the blade permits simultaneous punching and shearing. However, the pressures exerted on the punches in such a slug forming machine can lead to considerable wear and breakage since the stroke needed for the shearing operation is considerably longer and requires more pressure than is needed for the punching alone. In such a case, the punches would have to be hardened steel to reduce wear, yet even using the more expensive hardened steel, wear will still be a major problem.
Thus, there is need for a flying shear device which is of the slugless type for economy, yet can perform a flying punch operation on the panel as the shearing operation is performed to produce accurate holes without inducing inordinate wear on the punches. Such a machine is herein disclosed.